In the past, for example, a side airbag having a shape shown in FIG. 6 was known as a side airbag stored in a seat in a vehicle. The side airbag 50 of the related art, which is shown in FIG. 6, has an airbag portion 52 for protecting a passenger from a side impact in an emergency case and an inflator 51 that supplies gas to inflate the airbag portion 52.
In addition, a shape having a plurality of air bag portions was known as the shape of an airbag of the related art. For example, Japanese Unexamined Patent Application Publication No. 2008-30620 describes a side airbag having two airbag portions and an inflator that supplies air to the two airbag portions at the top and bottom.